System information (SYS INFO) contains network parameters sent to MS through air interface(Um), including network identity parameters, cell selection parameters, system control parameters and network function parameters. By reading system information, MS can access the network, perform cell selection, fully utilize various services provided by the network, and achieve favorable cooperation with the network. SYS INFO can be divided into two parts:
SYS INFO sent on BCCH, including SYS INFO 1, 2, 2BIS, 2TER, 3, and 4, which are used by MS in idle mode.
SYS INFO sent on SACCH, including system information 5, 5BIS, 5TER, and 6, which are used by MS in dedicated mode. Additionally Huawei BSC supports the system information 7 and 13 to support GPRS.
BCCH system information belongs to common channel information. SACCH system information basically belongs to TRX management information. Common channel and TRX management information should be selected in order to observe all the system information when tracing on the layer 3 messages of radio interface.
Version G2BSC3203.0520B onwards, the system information 1, 2, 2TER, 3, 4, 5, 5TER, and 6 are default when system information is transmitted to cells. System information 2BIS and 5BIS are conditionally transmitted on GSM1800 cells. It will be explained in the following section.